Most two-cycle engines and even some recently developed four-cycle engines require a continuous supply of lubricant. In such internal combustion engines the lubricant is supplied continuously either by pumping small amounts of for example oil through a separate lubrication system to the vital parts of the engine or by mixing the lubricant in the fuel at the time of refueling the fuel tank for said engine.
Different systems have previously been developed to avoid that, for example two-cycle engines, sustain damage due to that the necessary lubricant for the engine is not present. These systems are typically designed as part of a separate lubrication system, including a separate lubricant tank, whereas the presence of lubricant is indicated by the system, e.g. by means of a float device etc. connected to a gauge or a indicator lamp or directly to the ignition system for the engine.
In some engine applications it has proven to be impractical to use a separate lubricant tank and/or a pump system to continuously supply the lubricant. Examples are hand held small two-cycle engines, used among others in chain saws, grass trimmers and cut-off saws, that are used in varying running conditions and thus the separate lubrication systems have not been successfully applied. Due to the impracticality of the separate lubrication systems the lubricant is usually added/mixed to the fuel before the fuel is filled into the fuel tank of the engine.
One problem of supplying the lubricant to the engine through supply together with the fuel is to detect if a lubricant is present in the fuel or not. It is however common that a lubricant that is intended to be mixed in fuel is distinctly colored by, for example, a blue, green or red die. When said colored lubricant is mixed in the fuel the mixture of lubricant and fuel will also be fairly strong colored and can thus visually be inspected in for example a transparent vessel. Such an inspection is however dependent on that the operator is aware of the problem and that he actively takes the measures to check if lubricant has been added to the fuel. There is therefore nothing that prevents an engine from being operated even though an improper mixture of fuel/lubricant is used.
The result of operating an internal combustion engine that requires a continuous supply of lubricant without lubrication is usually significant engine damage before the operator gets any indication of that the lubricant is not present.